Premium
e IF 5 B employs a novel domain release mechanism to catalyze ribosomal subunit joining
Author(s) -
Kuhle Bernhard,
Ficner Ralf
Publication year - 2014
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/embj.201387344
Subject(s) - biology , protein subunit , domain (mathematical analysis) , mechanism (biology) , ribosomal rna , microbiology and biotechnology , biochemistry , gene , mathematical analysis , philosophy , mathematics , epistemology
Abstract e IF 5 B is a eukaryal translational GTP ase that catalyzes ribosomal subunit joining to form elongation‐competent ribosomes. Despite its central role in protein synthesis, the mechanistic details that govern the function of e IF 5 B or its archaeal and bacterial ( IF 2) orthologs remained unclear. Here, we present six high‐resolution crystal structures of e IF 5 B in its apo, GDP ‐ and GTP ‐bound form that, together with an analysis of the thermodynamics of nucleotide binding, provide a detailed picture of the entire nucleotide cycle performed by e IF 5 B . Our data show that GTP binding induces significant conformational changes in the two conserved switch regions of the G domain, resulting in the reorganization of the GTP ase center. These rearrangements are accompanied by the rotation of domain II relative to the G domain and release of domain III from its stable contacts with switch 2, causing an increased intrinsic flexibility in the free GTP ‐bound e IF 5 B . Based on these data, we propose a novel domain release mechanism for e IF 5 B / IF 2 activation that explains how e IF 5 B and IF 2 fulfill their catalytic role during ribosomal subunit joining.